Apparatus for sampling a process stream under vacuum



1965 A. ANDERSON ETAL 3,209,598

APPARATUS FOR SAMPLING A PROCESS STREAM UNDER VACUUM Filed March 27. 1963 Pici/ v52 FL U/D ANAL r252 l /0 VACUUM PUMp as CGLLECTOE 20 INVENTORS 420/5 L, A/v/xeso/v United States Patent 3,209,598 APPARATUS FOR SAMPLING A PROCESS STREAM UNDER VACUUM Ardis L. Anderson, Ponca City, Okla., and Erik Wiilt, South Charleston, W. Va., assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaware Filed Mar. 27, 1963, Ser. No. 268,392 11 Claims. (Cl. 73-422) This invention relates to improvements in sampling apparatus, and more particularly, but not by way of limitatron, to an apparatus particularly adapted for sampling a process stream under vacuum.

It is known to persons skilled in the above-cited art to which the invention is particularly applicable to provide for the taking of test samples, automatic samplers which tap otf a small sample stream from a process stream and pump it through an analyzer. It is also known to provide automatic samplers for the taking of samples of solids in the form of granular or pulverant materials. However, a serious problem arises when it is desired to extract a sample from a process stream or fluid stream which is flowing under a vacuum. It is diflicult to provide a suitable pump with suflicient suction to overcome the vacuum on the process stream and to extract the desire-d sample. The period of time required to extract the desired sample from a process stream may also be an important factor since the characteristics of the sample may change with time, and the process stream from which the sample was taken continues to flow, thereby reducing the precision with which it may be monitored.

The present invention contemplates a novel system for extracting and analyzing a fluid sample from a process or fluid stream flowing under vacuum. This novel system includes a collector which, after being evacuated to a vacuum at least equal to the vacuum on the fluid stream, is placed in communication with an accumulator receiving the fluid stream so that a fluid sample is extracted therefrom. After the collector has received the requisite fluid sample, the vacuum thereon is reduced to atmospheric pressure. Then the fluid sample is withdrawn from the collector and driven through a fluid analyzer. From the analyzer, the fluid may be returned to the process stream from which it was extracted.

Accordingly, it is an object of the present invention to provide a novel system for extracting and analyzing a fluid sample from a process stream under vacuum.

It is another object of the present invention to provide a novel sampling system which quickly extracts a fluid sample from a process stream so that it may be analyzed with a minimum of delay.

It is still another object of the present invention to provide a novel sampling system which extracts and analyzes a small sample from a process stream with a minimum of delay thereby providing closer supervision of the process.

And yet, another object of the present invention is to provide a novel sampling system for extracting and analyzing a sample from a process stream, which system is automatic in operation, and which may be left unattended without creating a safety hazard.

A further object of the present invention is to provide a novel system for extracting and analyzing a fluid sample from a process stream, by which system the fluid sample is ultimately returned to the process stream, thereby keeping the environment of the system clean and eliminating the need for disposing of waste samples.

It is a still further object of this invention to provide a novel sampling system for extracting and analyzing a sample from a process stream, in which system the sample is not exposed to air, thereby eliminating the possibility of contamination of the sample and reducing the possibility Ice of the creation of a safety hazard in the sampling of pyrophoric and high volatile liquids.

It is another object of this invention to provide a system for sampling and analyzing a process stream under vacuum, in which system the sampling portion of the system is synchronized for actuation according to the analytical period of the analyzing portion of the system.

Other objects and advantages will be evident from the following detailed description, when read in conjunction with the accompanying drawing which illustrates our invention.

In the drawing, reference character 10 generally indicates a fluid sampling system embodying the present invention. A receiver or accumulator 12 having an inlet conduit 14 and an outlet conduit 16 receives a process or fluid stream 18 which flows under a predetermined vacuum. A suitable sample collector 20 communicates with the lower portion of the receiver 12 through a conduit 22, having a small diameter. The collector 20 preferably has a capacity of one-half to one pint, depending upon the particular fluid analyzer being used in the system 10. A solenoid operated valve 24 is interposed in the conduit 22 to control the flow of fluid from the receiver 12 to the sample collector 20.

A suitable vacuum pump 26 communicates with the sample collector 20 through a conduit 28 having a small diameter. A solenoid controlled valve 30 is interposed in the conduit 28 to control the communication of the collector 20 with the vacuum pump 26. The collector 20 communicates with the atmosphere through a conduit 32 having a small diameter. A solenoid controlled valve 34 is interposed in the conduit 32 to allow the collector 20 to be selectively vented to the atmosphere through conduit 32. Although the conduit 32 is shown in the drawing as having a relatively small length, it will be apparent that the conduit, in fact, may extend a suflicient distance away from the immediate environment of the sampling system 10 to preclude the creation of a safety hazard in the venting of the sample collector 20 if the collector were to contain highly volatile samples. Also, if it is desired to preclude contamination of a sample in the collector 20, a suitable inert gas may be introduced under pressure through the conduit 32 to raise the pressure in the collector to a desired level.

The collector 20 communicates with a suitable fluid analyzer 36 through a conduit 38 having a small diameter.

A more specific aspect of this invention is an embodiment which is especially adapted for a periodic or intermittent sampling of the process stream. In this embodiment the fluid analyzer 36 may comprise a chromatographic process stream analyzer which synchronizes a periodic and sequential operation of the valves of the system 10 in accordance with the analytical period of the analyzer.

A commercial example of this instrument is the Greenbrier Model 114X which is made by Greenbrier Instruments, Incorporated, Greenbrier, West Virginia. This in strument automatically operates unattended to intermittently analyze a fluid stream, using the chromatographic principle to separate the components of the fluid, and, using a thermal conductivity cell to determine the concentration of the components after separation. The output of the instrument is a millivolt signal which varies with time and is displayed on a strip chart recorder. This output signal may also be used for data logging, computers, or for process control. The analyzer 36 is also provided with a suitable clock mechanism for a periodic sequential operation of the system 10 in synchronism with the analytical period of this analyzer 36, as will be hereinafter set forth more fully.

A solenoid operated valve 40 and a suitable pump 42 are interposed in the conduit 38. The valve 40 controls the period during which the pump 42 may withdraw fluid from the collector 20 and direct it to the analyzer 36 through the conduit 38. The fluid analyzer 36 communicates with the receiver 12 through a conduit 44 having a small diameter. A solenoid controlled valve 46 is interposed in the conduit 44 to allow fluid flowing through the analyzer 36 to be drawn by the vacuum within the receiver 12 through the conduit 44 for return to the receiver 12. The solenoid controlled valves 24, 30, 34, 40, 46, the vacuum pump 26, and the pump 42 are controlled in a periodic and sequential operation by the clock mechanism of the fluid analyzer 36.

Operation In describing the operation of the novel sampling system 10, let it be initially assumed that the valves 24, 30, 34, 40 and 46 are closed and the system is in an inoperative position. The receiver or accumulator 12 receives a process stream through inlet 14 and discharges the same through an outlet 16 with a certain portion thereof being accumulated within the receiver, as indicated in the drawing. The vacuum pump 26 is then started and the valve 30 is opened to allow the pump 26 to evacuate the collector to a vacuum lower than the vacuum on the fluid 18 contained in the receiver 12. When this predetermined vacuum has been attained, the valve 30 closes and the vacuum pump 26 is stopped. The valve 24 is then opened to allow the collector 20 to withdraw the fiuid sample from the receiver 12 through conduit 22. When the requisite sample has been withdrawn which, for purposes of illustration, may comprise the filling of the collector 20, the valve 24 is closed.

It is to be understood that the vacuum on the collector 20 is preferably greater than the vacuum on the receiver 12 so that fluid is drawn into the collector 20 regardless of its physical relationship to the receiver 12. However, the collector 20 may be evacuated to substantially the same vacuum as on the receiver 12 and the collector 20 placed below the receiver 12 so that fluid flows by gravity into the collector.

The valve 34 is then opened to allow the collector 20 to communicate with the atmosphere through the conduit 32 and to thereby raise the pressure within the collector to atmospheric pressure. The valve 34 is closed when the pressure within the collector 20 reaches atmospheric pressure. The valve 40 in the conduit 38 and the valve 46 in the conduit 44 are then opened to allow the pump 42 to withdraw the fluid from the collector tank 20 and discharge said fluid through the analyzer 36 back into the receiver 12. When the fluid in the sample collector 20 has been completely withdrawn and the composition thereof determined by the analyzer 36, the valves 40 and 46 close and the pump 42 is turned ofl to return the sampling system 10 to an inoperative position. The system 10 may then be recycled as desired for a close monitoring of the process stream 18.

From the foregoing, it will be apparent that the present invention provides a novel sampling system which extracts and analyzes a sample from a process stream under vacuurn. The novel sampling system is automatic in operation and operates in a minimum of time to preclude deleterious changes in the sample and to provide a close monitoring of the process stream. This novel sampling apparatus also substantially precludes contamination of the sample and further precludes creation of safety hazards in the immediate vicinity of the apparatus. Since the novel sampling system provides for a return of the fluid samples to the process stream, the need for disposing of waste samples is eliminated and the immediate environment of the apparatus is kept clean and free from safety hazards. Finally, it will be apparent that the present invention provides a novel sampling system which is simple in construction, may be economically manufactured and which has a long service life,

Changes may be made in the combination and arrangement of parts or elements as heretofore set forth in the specifications and shown in the drawing, it being understood that changes may be made in the precise embodiment disclosed without departing from the spirit and scope of the invention as defined in the following claims.

We claim:

1. A system for extracting and analyzing a fluid sample from a fluid stream under vacuum, comprising:

a receiver adapted to receive fluid under vacuum from the fluid stream,

a collector selectively communicating with the receiver,

means for evacuating the collector,

means to reduce the vacuum in the collector after fluid has been drawn into the evacuated collector,

a fluid analyzer communicating with the collector and the fluid streams, and

a fluid pump arranged to withdraw fluid from the collector and discharge it through the fluid analyzer back into the fluid stream so that the composition of the fluid may be determined.

2. A system for extracting and analyzing a fluid sample from a fluid stream under vacuum, comprising:

a receiver adapted to receive fluid under vacuum from the fluid stream,

a collector selectively communicating with the receiver,

means to create a vacuum in the collector at least equal to the vacuum on the fluid stream,

means for introducing a volume of fluid from the fluid stream into the collector,

means to reduce the vacuum in the collector after the fluid has been introduced into the collector,

a fluid analyzer arranged to communicate with the collector and the fluid stream, and

a fluid pump arranged to withdraw fluid from the collector and discharge it through the fluid analyzer back into the fluid stream so that the composition of the fluid may be determined.

3. A system for extracting and analyzing a fluid sample from a fluid stream under vacuum, comprising:

a receiver adapted to receive fluid under vacuum from the fluid stream,

a collector arranged to communicate with the receiver,

means to create a vacuum in the collector at least equal to the vacuum on the fluid stream,

means to direct a predetermined volume of fluid from the fluid stream into the collector,

means to reduce the vacuum on the collector after it has received said volume of fluid,

a fluid analyzer communicating with the collector and the receiver, and

means to withdraw fluid from the collector after the vacuum has been reduced and to discharge said fluid through the fluid analyzer back into the receiver so that the composition of the fluid may be determined.

4. A system as defined in claim 3 wherein the means placing a vacuum on the collector is a vacuum pump and the means reducing the vacuum on the collector is a valve which vents the tank to atmosphere.

5. A system as defined in claim 3 wherein the means withdrawing the fluid from the collector is a pump.

6. A system for extracting and analyzing a fluid sample from a fluid stream under vacuum, comprising:

a receiver adapted to receive fluid under vacuum from the fluid stream,

a collector,

a vacuum pump which evacuates the collector to a vacuum less than that on the fluid stream,

conduit means connecting the collector to the receiver so that a fluid sample may be withdrawn from the receiver,

means to raise the pressure in the collector to atmospheric pressure after the sample has been withdrawn,

a fluid analyzer,

conduit means connecting the fluid analyzer to the collector and to the receiver, and

means to withdraw the fluid sample from the collector and drive it through the fluid analyzer back into the receiver so that the composition of the sample may be determined.

7. A system as defined in claim 6 wherein the means raising the pressure on the collector tank is a valve which vents the tank to the atmosphere.

8. A system as defined in claim 6 wherein the means which withdraws the fluid sample from the collector and drives it through the fluid analyzer back into the receiver is a pump.

9. A system for extracting and analyzing a fluid sample from a fluid stream under a predetermined vacuum, comprising:

a receiver adapted to receive fluid under vacuum from the fluid stream,

a collector,

a first conduit connecting the collector to the receiver,

a vacuum pump connected to the collector for evacuating the collector to a vacuum lower than the vacuum on the fluid stream,

a valve interposed in said conduit, when said valve is opened for a predetermined period of time the collector withdraws a fluid sample from the receiver,

a valve which vents the collector to atmosphere so that the pressure in the collector is raised to atmospheric pressure after the collector has received the aforesaid sample,

a fluid analyzer,

second and third conduits respectively connecting the analyzer to the collector and to the receiver,

a pump interposed in the second conduit to withdraw the fluid sample from said collector and drive it through the analyzer to the receiver so that the composition of the sample may be determined,

a valve interposed in the second conduit, when said valve is opened the fluid sample flows from the collector to the analyzer, and

a valve interposed in the third conduit, when said valve is opened the fluid driven through the analyzer is returned to the receiver.

10. A system as defined in claim 9 wherein means are connected to said valves for synchronizing the opening and closing thereof with the analytical period of said fluid analyzer.

11. A system as defined in claim 9 wherein the fluid analyzer is a chromatographic stream analyzer.

References Cited by the Examiner UNITED STATES PATENTS 5/56 Eckstrom 73-434 8/61 Parker et al. 73421 

1. A SYSTEM FOR EXTRACTING AND ANALYZING A FLUID SAMPLE FROM A FLUID STREAM UNDER VACUUM, COMPRISING: A RECEIVER ADAPTED TO RECEIVE FLUID UNDER VACUUM FROM THE FLUID STREAM, A COLLECTOR SELECTIVELY COMMUNICATING WITH THE RECEIVER, MEANS FOR EVACUATING THE COLLECTOR, MEANS TO REDUCE THE VACUUM IN THE COLLECTOR AFTER FLUID HAS BEEN DRAWN IN TO THE EVACUATED COLLECTOR, A FLUID ANALYZER COMMUNICATING WIT THE COLLECTOR AND THE FLUID STREAMS, AND A FLUID PUMP ARRANGED TO WITHDRAW FLUID FROM THE COLLECTOR AND DISCHARGE IT THROUGH THE FLUID ANALYZER BACK INTO THE FLUID STREAM SO THAT THE COMPOSITION OF THE FLUID MAY BE DETERMINED. 